Ameliorative symbiosis of Serratia fonticola (S1T1) under salt stress condition enhance growth-promoting attributes of Cucumis sativus L

Salinity stress is a combination of ionic, osmotic, and oxidative stressors that have a negative impact on crop growth and production. In the present study, experiments were conducted to investigate the role of multi-traits Serratia fonticola (S1T1) on Cucumis sativus L. growing under salinity stress (200 mM). The control plants had stunted growth, while S. fonticola (S1T1) root zone treated plants revealed significantly higher fresh (26.71%) and dry (24.8%) biomass, and improved level of chlorophyll content (25.24%) followed by foliar application of S. fonticola (S1T1) under salt stress. Similarly, increased water potential (15-20%), decreased (14-20%) endogenous abscisic acid (ABA) and lower electrolytic leakage (21-35%) were additional proof of the beneficial impacts of root zone inoculated C. sativus L. under salt stress conditions. Antioxidant analysis revealed a decrease in malondialdehyde (MDA) content (13-31%), H2O2 content (15-36%) and superoxide anion (SOA) (11-32%) while an increase in antioxidant enzymes such as catalase (CAT) (13.2-35.5%) and superoxide dismutase (SOD) (9.61-29.7%). The root zone and foliar application of S. fonticola (S1T1) on cucumber plants improved salt-stress tolerance by up-regulating the transcript accumulation of ion transporter genes HKT1 (2-3-folds), NHX (18.2-folds) and SOS1 (8.2-folds). Conclusively, the symbiotic association of S. fonticola (S1T1) can alleviate the antagonistic effects of salinity stress, improve cucumber plant growth and could be utilized as an eco-friendly biofertilizer or microbial plant biostimulant (MBPs) under salt stress conditions.

Automated summary

This study investigated the role of multi-traits Serratia fonticola (S1T1) in promoting the growth of Cucumis sativus L. under salinity stress (200 mM). The results showed that plants treated with S. fonticola (S1T1) in the root zone had significantly higher fresh and dry biomass, as well as improved chlorophyll content, compared to the control plants. Additionally, the inoculated plants exhibited increased water potential, decreased abscisic acid levels, and lower electrolytic leakage, indicating the beneficial effects of S. fonticola (S1T1) on cucumber plants under salt stress conditions. Antioxidant analysis revealed a decrease in MDA and H2O2 content, as well as an increase in catalase and superoxide dismutase activity. The symbiotic association of S. fonticola (S1T1) was also found to up-regulate the transcript accumulation of ion transporter genes, contributing to salt-stress tolerance in cucumber plants. In conclusion, the use of S. fonticola (S1T1) as a biofertilizer or microbial plant biostimulant could help alleviate the negative effects of salinity stress and improve cucumber plant growth.